Dispersed electrolyte and electroless plating solution for particle-containing nickel and nickel alloy layers

Abstract

The present invention relates, among other things, to a dispersed electrolyte for the electrochemical deposition of particle-containing nickel or particle-containing nickel alloy layers. The dispersed electrolyte includes: 2 to 200 g / L of nickel ions; a total of 1 to 200 g / L of at least one particle selected from the group consisting of inorganic piezoelectric particles, conductive ceramic particles, and combinations thereof; an anionic and / or nonionic dispersant; and water. In the case of nickel alloys, the dispersed electrolyte comprises: ions of at least one other metal selected from the group consisting of transition metals, noble metals and combinations thereof, the total concentration of the ions of the other metals being at most 40 g / L; and / or at least one non-metallic compound selected from the group consisting of phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds, carbon compounds and combinations thereof, the total concentration of said non-metallic compounds being at most 50 g / L. The pH value is 2.0 to 7.0. With a dispersed electrolyte, a particle-containing nickel or nickel alloy layer may be deposited by an electrochemical process onto a metal or metallized substrate.

Description

Technical Field

[0001] The present invention relates to a dispersed electrolyte for electrodepositing a particulate nickel or nickel alloy layer, a bath for electrodepositing a particulate nickel or nickel alloy layer, a method for electrophoretically coating or electrodepositing a substrate with a particulate nickel or nickel alloy layer, a coated substrate having a particulate nickel or nickel alloy layer, and an electrochemical cell comprising the coated substrate. Background Technology

[0002] For many electronic applications, it is desirable to partially or completely replace precious metals with more cost-effective non-precious metals. In such cases, in addition to good electrical performance, corrosion resistance is also desired for durable and therefore sustainable electronic components (e.g., contacts or electrodes). However, many non-precious metals and their alloys have insufficient corrosion resistance, for example, insufficient resistance to aqueous alkaline media. Therefore, a corrosion-resistant protective layer is needed for electronic components.

[0003] For example, coatings made of nickel or nickel alloys can be used for use in alkaline aqueous media. These coatings can be electrodeposited via an electrolyte or electrolessly deposited (i.e., chemically deposited) via a plating bath. Therefore, such nickel and nickel alloy layers can serve as a more economical alternative to precious metals. However, they generally exhibit poorer electrical properties compared to precious metals. For example, these poorer electrical properties may manifest as increased contact resistance compared to other metals. Furthermore, overvoltages can be observed in electrochemical reactions in aqueous media, particularly in alkaline aqueous media, and these overvoltages are typically caused by kinetic inhibition of the reaction. Therefore, it is desirable to develop coatings that can ensure good corrosion resistance while simultaneously improving electrical properties (especially reducing overvoltages in alkaline aqueous media). In addition, there is a need for compositions and methods that can economically produce these coatings. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide an electrolyte for electrodeposition and a plating solution for electrodeposition of nickel or nickel alloy layers, said nickel or nickel alloy layers being corrosion-resistant in an alkaline range and capable of reducing overvoltages in electrochemical reactions in aqueous alkaline media. Other objects include providing a method for coating a substrate with such a nickel or nickel alloy layer, said method using an electrolyte or plating solution for electrodeposition, providing a coated substrate, and providing its use.

[0005] According to the independent claims, these objectives are achieved by: a dispersed electrolyte for electrodepositing a particulate nickel or nickel alloy layer; a plating solution for electrodepositing a particulate nickel or nickel alloy layer; a method for electrophoretically coating or electrodepositing a substrate with a particulate nickel or nickel alloy layer, said method using a dispersed electrolyte or plating solution; a coated substrate; and an electrochemical cell comprising said coated substrate. Optional and preferred configurations are given below and in the dependent claims. Attached Figure Description

[0006] Data shows: Figure 1 Scanning electron microscope image of the particulate layer in Example 1; Figure 2 Scanning electron microscope images of the particulate layer in Example 2; Figure 3 Scanning electron microscope images of the particulate layer in Example 3; Figure 4 Scanning electron microscope images of the layers in Comparative Example 1; Figure 5 shows A) an optical micrograph and B) a scanning electron micrograph of the cross section of Example 2; Figure 6 shows A) an optical micrograph and B) a scanning electron micrograph of the cross section of Example 3; Figure 7 Optical micrograph of the cross section of Comparative Example 1; Figure 8 Scanning electron microscope image of the particulate layer in Example 4; Figure 9 Scanning electron microscope image of the particulate layer in Example 5; Figure 10 Scanning electron microscope image of the particulate layer in Example 6; Figure 11 shows A) an optical micrograph and B) a scanning electron micrograph of a cross section of Example 5; Figure 12 shows A) an optical micrograph and B) a scanning electron micrograph of the cross section of Example 6; Figure 13 Scanning electron microscope image of the particulate layer in Example 7; Figure 14 Scanning electron microscope image of the particulate layer in Example 8; Figure 15 Scanning electron microscope image of the particulate layer in Example 9; Figure 16 shows A) an optical micrograph and B) a scanning electron micrograph of a cross section of Example 8; Figure 17 shows A) an optical micrograph and B) a scanning electron micrograph of the cross section of Example 9. Detailed Implementation

[0007] This invention provides a dispersed electrolyte for electrodepositing particulate nickel layers or particulate nickel alloy layers. The dispersed electrolyte comprises: - Nickel ions at concentrations of 2 to 200 g / L; - The particles are selected from at least one of the following: inorganic piezoelectric particles, conductive ceramic particles and combinations thereof, wherein the total concentration of the particles is 1 to 200 g / L; - At least one dispersant selected from the following: anionic dispersants, nonionic dispersants, and combinations thereof; - Optionally, ions selected from at least one of the following other metals: transition metals, noble metals and combinations thereof, wherein the total concentration of the ions of the other metals is at most 40 g / L; - Optionally, a nonmetallic compound, distinct from the dispersant and selected from at least one of the following: phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds, carbon compounds, and combinations thereof, wherein the total concentration of said nonmetallic compound is at most 50 g / L; and - water.

[0008] The pH value of the dispersed electrolyte is 2.0 to 7.0. The dispersed electrolyte is also referred to as "electrolyte" below.

[0009] The inventors unexpectedly discovered that the dispersed electrolyte according to the invention enables the electrodeposition of uncharged particles together with a nickel layer or nickel alloy layer, thereby forming a particle-containing nickel or nickel alloy layer. Therefore, the deposited nickel or nickel alloy layer contains particles of one or more inorganic piezoelectric materials and / or one or more conductive ceramic materials in addition to nickel or nickel alloy. The deposited nickel alloy typically has a high nickel content of at least 65 wt%, preferably at least 75 wt%, more preferably at least 85 wt%, and even more preferably at least 90 wt%, relative to the alloy. The particles are not included in the nickel alloy.

[0010] When the electrolyte contains ions of other metals selected from transition metals and noble metals, and / or non-metallic compounds, in addition to nickel ions, nickel alloys are electrodeposited. These other metal ions are electrodeposited together with the nickel. The non-metallic compounds can decompose during the electrodeposition process and serve as precursor compounds for incorporating the corresponding non-metallic atoms (P, S, Se, Te, and / or C) into the alloy. These other metals are different from nickel. The non-metallic compounds are different from the dispersant.

[0011] Furthermore, surprisingly, the particles in inorganic piezoelectric or conductive ceramic materials are able to reduce the overvoltage at the interface of electrochemical reactions in aqueous media, especially in aqueous alkaline media, compared to corresponding nickel or nickel alloy layers without particles. Due to the lower overvoltage, less current is required for the same electrochemical reaction, thus improving the economics of the reaction.

[0012] Electrolytes enable the electrodeposition of particulate nickel or nickel alloy layers on metallic or metallized substrates. This can be achieved using methods described below, which allow deposition over a wide range of temperatures and current densities. During deposition, particles are at least partially aligned on the surface of the particulate nickel or nickel alloy layer, thus forming part of the surface. The particulate nickel or nickel alloy layer is typically produced as the final layer (i.e., the outermost layer) on the substrate, for example, as part of a monolayer or layer system.

[0013] Furthermore, surprisingly, despite the presence of some essentially foreign particles in the nickel or nickel alloy layer, the particulate nickel or nickel alloy layer exhibits good corrosion resistance in the weakly acidic range, and especially in the alkaline range, comparable to that of the corresponding particulate-free nickel or nickel alloy layer. Therefore, particulate nickel or nickel alloy layers are suitable for use as corrosion protection layers, particularly under alkaline conditions.

[0014] Therefore, the dispersed electrolyte according to the invention can form a layer that provides good corrosion protection and reduces the overvoltage of electrochemical reactions in aqueous media, thereby achieving these advantageous properties simultaneously in a single layer. Thus, a particulate nickel or nickel alloy layer can be effectively used as a protective layer, i.e., particularly as the outermost layer on components, especially electronic components, such as contacts or electrodes.

[0015] The dispersed electrolyte according to the invention comprises at least one type of particles selected from: inorganic piezoelectric particles, conductive ceramic particles, and combinations thereof. Therefore, these particles may consist of one or more inorganic piezoelectric particles and / or one or more conductive ceramic particles.

[0016] These particles can be made of inorganic piezoelectric materials, which can be single-crystal or polycrystalline. The piezoelectric effect can occur in non-centrosymmetric point groups (crystal groups). Therefore, the unit cell of this material does not have a reversal center. Thus, for example, cubic point groups with reversal centers do not exhibit piezoelectricity. If piezoelectric and non-piezoelectric modifications exist in the inorganic material, only the piezoelectric modification of the particles is considered. For example, barium titanate (BaTiO3) can exist in a perovskite structure and its cubic modification. Because the cubic modification is not piezoelectric, it is not included in the particle count. Another example is boron nitride (BN). Since hexagonal BN is piezoelectric, it can be used as particles according to the present invention. Cubic boron nitride is not piezoelectric and therefore is also not included in the particle count.

[0017] These particles can also be made of conductive ceramic materials. Non-ceramic conductive particles (e.g., particles composed of metals) are not counted as particles.

[0018] According to the present invention, inorganic piezoelectric particles and conductive ceramic particles are not limited thereto. Materials doped with foreign atoms can also be used as inorganic piezoelectric particles. For example, the particles can be selected from: BN (hexagonal crystal system), AlN, ZnO, GaPO4, M1 2y MA 1-y [MB x Ti 1-x O3, M1 2y MA 1-y MC x Zr 1-x O3, M1 2y MA 1-y [MD x Mn 1-x O3, M1 2y MA 1-y [ME x Hf 1-x O3, M1[MF x Nb 1-x O3, M1[MG x V 1-x O3, M1[MH x Ta 1-x O3, TiN, TiC, TiB2, Ti2CN, B4C, WC, and combinations thereof. In the general formula, the following conditions apply: M1 is independently selected from at least one of the following elements in each case: Li, Na, and K, preferably Li; MA is independently selected from at least one of the following elements in each case: Ca, Sr, Ba, Pb, and La; MB is selected from Zr, Hf, Mn, and Mg. 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 MC is selected from Hf, Mn, and Mg. 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 MD is selected from Hf and Mg 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ME is selected from Mg 1 / 3 Nb 2 / 3Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MF is selected from V, Ta and Mn; MG is selected from Ta and Mn; MH is Mn; x independently satisfies 0≤x≤1 in each case; y independently satisfies 0≤y≤1 in each case.

[0019] These particles are specifically selected from BN (hexagonal crystal system), AlN, ZnO, GaPO4, and Li. 2y MA 1-y [MB x Ti 1-x O3, Li 2y MA 1-y MC x Zr 1-x O3, Li 2y MA 1-y [MD x Mn 1-x O3, LiNbO3, LiVO3, LiMnO3, LiTaO3, TiN, TiC, TiB2, Ti2CN, B4C, WC, and combinations thereof. In the general formula, the following conditions apply: MA is independently selected from at least one of the following elements in each case: Ca, Sr, Ba, Pb, and La; MB is selected from Zr, Mn, and Mg. 1 / 3 Nb 2 / 3 MC is selected from Mn and Mg 1 / 3 Nb 2 / 3 MD is Mg 1 / 3 Nb 2 / 3 x independently satisfies 0 ≤ x ≤ 1 in each case; y independently satisfies 0 ≤ y ≤ 1 in each case.

[0020] Of the aforementioned materials, TiN, TiC, TiB2, Ti2CN, B4C, and WC are conductive ceramic materials, while the remainder are inorganic piezoelectric materials. According to a preferred embodiment, the particles are selected from inorganic piezoelectric particles.

[0021] According to another preferred embodiment, the inorganic piezoelectric particles are selected from BN (hexagonal crystal system), AlN, ZnO, GaPO4, Li2[Zr] x Ti 1-x O3, Li 2y MA 1-y [Zr x Ti 1-x O3、MA[Zr x Ti 1-x O3, Pb[Zr x Ti 1-xO3, LaMnO3, and LiNbO3 and combinations thereof. The following conditions apply in the general formula: MA is independently selected from at least one of the following elements in each case: Ca, Sr, and Ba; x independently satisfies 0 ≤ x ≤ 1 in each case; y independently satisfies 0 ≤ x ≤ 1 in each case. <y<1。

[0022] Furthermore, the particles are preferably selected from BN (hexagonal crystal system), AlN, BaTiO3, Li2ZrO3, Li2TiO3, CaTiO3, ZnO, LaMnO3, and Pb[Zr]. x Ti 1-x O3 (where x takes values ​​in the range of 0≤x≤1), LiNbO3, GaPO4 and combinations thereof, and especially preferably selected from BN (hexagonal crystal system), BaTiO3, CaTiO3, Li2ZrO3 and combinations thereof.

[0023] Particles selected from inorganic piezoelectric particles and / or conductive ceramic particles are contained in the dispersion electrolyte at a total concentration of 1 to 200 g / L. Specifically, the total concentration of particles in the dispersion electrolyte is 3 to 150 g / L, preferably 5 to 100 g / L, more preferably 8 to 80 g / L, and even more preferably 15 to 60 g / L. At these concentrations, the dispersion electrolyte can be thoroughly mixed, and an appropriate amount of particles can be deposited together with the nickel or nickel alloy layer, thereby effectively reducing the overvoltage of the electrochemical reaction in the aqueous medium.

[0024] Generally, the particle size should be smaller than the thickness of the desired nickel or nickel alloy layer containing the particles. For example, particle size can be adjusted by conventional grinding and / or sieving processes, which separate particles that are too large or too small. Suitable particles are usually also commercially available.

[0025] For particles with an aspect ratio less than 3.0, the average particle size is typically in the range of 20 nm to 20 µm, preferably in the range of 0.1 to 10 µm, and more preferably in the range of 0.5 to 8 µm. The aspect ratio refers to the ratio of the particle's maximum diameter to its minimum diameter. Therefore, the aspect ratio of spherical particles is 1. The aspect ratio of a particle can be determined by microscopic measurement of 20 randomly selected particles. Depending on the particle size, an optical microscope or an electron microscope with a reference can be used.

[0026] If the aspect ratio of the particles is 3.0 or higher, the average length of the particles is typically 0.1 to 90 µm, preferably 0.5 to 50 µm, and more preferably 0.8 to 20 µm. Particles with this aspect ratio are typically flat or elongated, such as needle-like or plate-like. Here, length refers to the maximum diameter of the particle.

[0027] Particle size can be determined using laser diffraction, according to ISO 13320:2020, for example, using a HELOS (Helium-Neon Laser Optical System) spectrometer. The average particle size is expressed as the D50 value. In the deposition layer, the average particle size can be determined in a planar or cross-sectional view using a microscope or electron microscope. For this purpose, at least 100 randomly selected particles should be considered to determine the average particle size.

[0028] In principle, any commonly used water-soluble nickel salt can be used as a dispersing electrolyte. The electrolyte also contains the corresponding anion of the nickel salt. For example, nickel sulfamate, nickel sulfate, nickel chloride, nickel bromide, nickel acetate, and combinations thereof are all suitable. Nickel sulfamate, nickel sulfate, nickel chloride, and combinations thereof are preferred. Various modifications of the nickel salt (e.g., hydrates) can be used as the electrolyte. According to a preferred embodiment, as a nickel ion counterion anion, the dispersing electrolyte comprises sulfamate, sulfate, chloride, bromide, acetate, and combinations thereof; preferably sulfamate, sulfate, chloride, and combinations thereof.

[0029] The concentration of nickel ions in the dispersed electrolyte is 2 to 200 g / L. Specifically, the concentration of nickel ions present in the electrolyte is 5 to 180 g / L, preferably 10 to 160 g / L, more preferably 20 to 150 g / L, and even more preferably 40 to 140 g / L. The concentrations shown are related to Ni... 2+ The form of nickel ions is relevant. At these concentrations, the electrolyte is storage stable and can be used economically at appropriate deposition rates.

[0030] Typically, when the nickel ion concentration is high, a high concentration of particles is used in the electrolyte. Typically, the weight ratio of nickel ions to particles is 20:1 to 1:3, preferably 10:1 to 1:2, and more preferably 5:1 to 1:2.

[0031] The layer deposited by the dispersive electrolyte is a particulate nickel layer or a particulate nickel alloy layer. A particulate nickel layer is preferred. The dispersive electrolyte used for the particulate nickel layer typically does not contain (except for unavoidable impurities) any other metal ions or non-metallic compounds selected from transition metals and / or noble metals that are electrodeposited together with nickel, or that decompose during electrodeposition to form a nickel alloy and serve as precursor compounds for incorporating the corresponding non-metallic atoms (P, S, Se, Te, and / or C) into the alloy. If a particulate nickel alloy layer is to be deposited in the dispersive electrolyte, it should contain such ions and / or non-metallic compounds.

[0032] If the dispersed electrolyte contains ions of at least one other metal selected from the group consisting of transition metals, noble metals, and combinations thereof, these metal ions are present at a total concentration of up to 40 g / L, preferably up to 30 g / L, more preferably up to 20 g / L, and even more preferably up to 10 g / L. In this embodiment, the weight ratio of nickel ions to other metal ions in the electrolyte is typically 80:20 or higher, preferably 85:15 or higher, more preferably 90:10 or higher, and even more preferably 95:5 or higher.

[0033] If the dispersed electrolyte contains at least one nonmetallic compound selected from the group consisting of phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds, and combinations thereof, these compounds are present at a total concentration of up to 50 g / L, preferably up to 30 g / L, more preferably up to 15 g / L, and even more preferably up to 5 g / L. The weight ratio of nickel ions to all phosphorus, sulfur, selenium, and tellurium atoms in at least one nonmetallic compound is typically 85:15 or higher, preferably 90:10 or higher, and more preferably 95:5 or higher. Therefore, the nonmetallic compound serves as a precursor compound for P, S, Se, Te, and / or C atoms in nickel alloys.

[0034] Other metals particularly include at least one element selected from the group consisting of Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb, and combinations thereof, preferably composed of the above elements. According to a preferred embodiment, the other metals include Fe, Co, Mo, or Cu, or are composed of the above metals. In other words, according to this embodiment, the electrolyte contains ions of one or more of these other metals, which can be electrodeposited together with nickel. The other metals can be added in the form of soluble salts.

[0035] The nonmetallic compound may in particular include at least one compound selected from the following: hypophosphite, urea, thiourea, thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, dimethyl telluride, xanthate, carbamate, ketone (e.g., benzenemethylacetone), aromatic aldehyde (e.g., naphthaldehyde), sulfonated castor oil, and combinations thereof, and preferably consists of the above compounds. During electrodeposition, the nonmetallic compound may decompose, and P, S, Se, Te, and / or C atoms may be incorporated into the nickel alloy accordingly. The nonmetallic compound preferably comprises one or more compounds selected from the following: thiourea, thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, xanthate, carbamate, naphthaldehyde, benzenemethylacetone (4-phenylbutenone), and sulfonated castor oil, or consists of the above compounds. According to this embodiment, S, Se, and / or C atoms are incorporated into the nickel alloy. S and / or Se are particularly preferred. The nonmetallic compound comprises at least one nonmetallic compound selected from the following: thiourea, thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide and combinations thereof, or is composed of the above compounds.

[0036] In principle, in addition to particles selected from inorganic piezoelectric particles, conductive ceramic particles and combinations thereof, the dispersed electrolyte may also contain other particles in order to change the properties of the nickel or nickel alloy layer containing particles.

[0037] According to another embodiment, as other particles, the dispersing electrolyte comprises conductive carbon material particles, preferably graphite, at a total concentration of 1 to 100 g / L, preferably 2 to 50 g / L, and more preferably 5 to 40 g / L. For example, these particles can improve the tribological properties of the particulate nickel or nickel alloy layer, or reduce the contact resistance relative to the metal. According to another embodiment, the dispersing electrolyte does not contain any conductive carbon material particles, and preferably, does not contain any other particles besides those selected from inorganic piezoelectric particles, conductive ceramic particles, and combinations thereof.

[0038] Preferably, the particle size of the other particles is as described in the above embodiments.

[0039] If the dispersed electrolyte contains other particles besides those selected from inorganic piezoelectric particles, conductive ceramic particles, and combinations thereof, the total amount of particles in the dispersed electrolyte (i.e., the total solids content) typically does not exceed 200 g / L, preferably 150 g / L, and more preferably 120 g / L. This prevents the dispersed electrolyte from exhibiting good miscibility and avoids excessive particle aggregation in the deposited layer.

[0040] To ensure effective dispersion of particles and (if present) other particles in the electrolyte, and to prevent the formation of large agglomerates of particles in the nickel or nickel alloy layer, the dispersing electrolyte according to the invention comprises at least one anionic and / or at least one nonionic dispersant. Anionic dispersants typically contain sulfate groups (OSO3). - ), sulfonate group (SO3) - ), carboxylate group (CO2) - ( ) or carboxyl (CO2H), these groups can exist as anions in aqueous solutions. Typically, H+ is added. + Alkali metal ions (preferably K) + and / or Na + ) and / or ammonium ions (NH4+) 4+ As counterions, they offer good water solubility, improve conductivity, and do not negatively impact electrodeposition. Therefore, the electrolyte also contains counterions of the anionic dispersant, preferably Na. + and / or K + At the pH value of the dispersed electrolyte, the sulfate and sulfonic acid groups are in a dissociated state, meaning they are not in a protonated state. Conversely, the carboxyl and carboxylate groups can be in equilibrium with each other.

[0041] Anionic and / or nonionic dispersants are typically used to disperse electrolytes at a total concentration of 0.1 to 100 g / L. In particular, the total concentration used in the electrolyte is 0.5 to 50 g / L, preferably 0.6 to 20 g / L. The required amount may vary depending on the type of dispersant. In principle, the more dispersant used, the better the particle dispersibility.

[0042] The weight ratio of the dispersant selected from anionic dispersants, nonionic dispersants and combinations thereof in the dispersing electrolyte, relative to the total amount of particles (i.e., particles and optional other particles, if present) (i.e., solid content), is particularly in the range of 25:1 to 1:80, preferably in the range of 5:1 to 1:60, and more preferably in the range of 1:5 to 1:50.

[0043] Examples of nonionic dispersants are polyalkylene glycol ethers, particularly polyethylene glycol ethers, alkyl polyglucosides or alkyl polyalkylene glycol ethers and combinations thereof.

[0044] According to a preferred embodiment, the dispersant comprises or consists of at least one anionic dispersant. In this case, preferably, at least 60 wt% or more, more preferably at least 80 wt% or more, of the dispersant is one or more anionic dispersants.

[0045] According to a more preferred embodiment, the dispersant comprises at least one anionic dispersant selected from: sulfate compounds having alkyl groups, aralkyl groups, or aromatic groups (in each case having up to 30 carbon atoms); sulfonate compounds having alkyl groups, aralkyl groups, or aromatic groups (in each case having up to 30 carbon atoms); and polymers containing carboxyl or carboxylate groups, or the dispersant is composed of the above substances.

[0046] More preferably, the anionic dispersant comprises at least one dispersant selected from: sulfate compounds having alkyl groups having 6 to 24 carbon atoms (preferably 10 to 20 carbon atoms); sulfate compounds having aralkyl groups having 6 to 24 carbon atoms (preferably 10 to 20 carbon atoms); sulfonate compounds having aromatic groups having 6 to 24 carbon atoms (preferably 6 to 14 carbon atoms); and combinations thereof. It may also comprise the same.

[0047] According to a particularly preferred embodiment, the anionic dispersant comprises at least one first anionic dispersant and at least one second anionic dispersant. The first anionic dispersant is selected from sulfate compounds having alkyl groups having 6 to 24 carbon atoms (preferably 10 to 20 carbon atoms), sulfate compounds having aralkyl groups having 6 to 24 carbon atoms (preferably 10 to 20 carbon atoms), and combinations thereof. The second anionic dispersant is selected from sulfonate compounds having aromatic groups having 6 to 24 carbon atoms (preferably 6 to 14 carbon atoms). The anionic dispersant preferably consists of at least one first anionic dispersant and at least one second anionic dispersant. Specifically, the weight ratio of the first anionic dispersant to the second anionic dispersant is 1:10 to 10:1, preferably 1:8 to 3:1, and more preferably 1:3 to 2:1. The combination of the first and second dispersants facilitates effective dispersion of particles and wetting of the substrate surface to be coated, thereby improving the deposition effect.

[0048] The sulfate compound having an alkyl group is preferably selected from alkyl sulfates, alkyl polyether sulfates, alkyl aryl polyether sulfates, and combinations thereof. In this case, the alkyl group having 6 to 24 carbon atoms, preferably 10 to 20 carbon atoms, is particularly derived from fatty alcohols. The polyether group is preferably a polyethylene glycol group.

[0049] Sulfonate compounds having aromatic groups having 6 to 24 carbon atoms (preferably 6 to 14 carbon atoms) are preferably selected from aryl sulfonates and polymers having aromatic sulfonate groups. Benzenesulfonic acid, phenolsulfonic acid, and naphthalenesulfonic acid (especially naphthalenesulfonic acid and its salts) are particularly preferred as aryl sulfonates. In polymers having aromatic sulfonic acid groups, the basic aromatic groups preferably each have 6 to 14 carbon atoms, and are particularly derived from benzenesulfonic acid, phenolsulfonic acid, and naphthalenesulfonic acid and their salts. For example, such polymers are condensation polymers of aromatic sulfonic acid compounds, such as condensation polymers of benzenesulfonic acid, phenolsulfonic acid, and naphthalenesulfonic acid and their salts with formaldehyde, especially naphthalenesulfonic acid-formaldehyde condensation polymers and their salts, such as Tamol from BASF SE. ® .

[0050] According to another preferred embodiment, the dispersing electrolyte further comprises a buffer compound having a pKa value of 2.5 to 10, and is preferably selected from boric acid, acetic acid, and combinations thereof, with boric acid being particularly preferred. The buffer compound is used, in particular, at a concentration of 1 to 80 g / L, preferably 10 to 70 g / L, and more preferably 20 to 60 g / L.

[0051] The pH value of the dispersion is in the range of 2.0 to 7.0, preferably in the range of 2.5 to 6.0, more preferably in the range of 3.0 to 5.0, for example 4. The pH value can be directly determined by the components of the dispersed electrolyte, or it can be adjusted by adding acid or base, especially by adding hydrochloric acid, sulfuric acid, sulfamic acid, sodium hydroxide, ammonia, potassium hydroxide or aqueous solutions thereof.

[0052] In addition, the dispersing electrolyte may contain conventional additives, such as those known to be used in conventional electrolytes for electrodepositing nickel layers or nickel alloy layers.

[0053] For example, commonly used conductive salts can be added to improve the conductivity of the electrolyte. Conductive salts are selected from, for example, sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, ammonium chloride, sodium acetate, potassium acetate, ammonium acetate, ammonium fluoride, ammonium bifluoride, sodium fluoride, and potassium fluoride, and combinations thereof, preferably from potassium chloride, potassium sulfate, sodium chloride, and sodium sulfate, and combinations thereof.

[0054] In addition, for example, a complexing agent can be added to the dispersed electrolyte to stabilize ions of other metals in the electrolyte and increase the deposition rate of other metals.

[0055] In principle, any complexing agent known to those skilled in the art and used in electrolytes can be used as a complexing agent. Preferably, the complexing agent is a chelated, water-soluble organic compound having at least three functional groups selected from amino, carboxyl, and carboxylic acid groups. Preferably, at least two of the functional groups are amino groups. The amino groups are selected from primary, secondary, and tertiary amino groups. More preferably, the complexing agent contains one or more secondary and / or tertiary amino groups. The functional groups providing coordination are typically spaced two or three carbon atoms apart, thereby enabling the formation of a stable chelate.

[0056] Particularly preferably, the complexing agent is selected from at least one of the following groups: EDTA, DETA, DOTA, and DOTATOC. EDTA is an abbreviation for ethylenediaminetetraacetic acid. DETA refers to diethylenetriamine. DOTA is an abbreviation for 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid. DOTATOC refers to a DOTA-derived complexing agent in which the DOTA molecule is bonded to the N-terminus of an octapeptide (particularly Phe-Cys-Tyr-Lys-Thr-Cys-Thr) via an amide bond. Other suitable complexing agents are hypophosphites, which can also lead to the incorporation of P atoms into nickel alloys.

[0057] Dispersed electrolytes can be formed by mixing or dissolving nickel salts, optional salts of other metals, optional nonmetallic compounds, and other components (i.e., dispersants, particles, water), as well as optional buffering compounds, conductive salts, and / or complexing agents. Particles, and (if present) other particles, can be added as powdered solids without the need to disperse these particles separately or by ultrasonically treating the mixture for dispersion. Stirring is preferred during electrolyte formation, and gentle heating may be necessary to accelerate the dissolution or dispersion of components. If necessary, the pH can be adjusted as described above.

[0058] The dispersible electrolyte according to the invention is advantageously capable of large-scale production and is therefore suitable for industrial applications. The electrolyte can be stored and any particles that may precipitate can be redispersed by methods such as stirring.

[0059] Another aspect of the invention relates to a method for electrophoretically coating a particulate nickel or nickel alloy layer onto a substrate. The method includes electrodepositing a particulate nickel layer or a particulate nickel alloy layer onto a metal or metallized substrate using a dispersed electrolyte according to at least one of the embodiments described herein. The method is carried out in a temperature range of 20 to 85°C, preferably 40 to 75°C, more preferably 50 to 70°C.

[0060] This method enables the production of a coated substrate having a particulate nickel layer or a particulate nickel alloy layer, which achieves the aforementioned advantages. In particular, it can be a coated substrate as described in more detail below. By this method, the particles are at least partially arranged on the surface of the particulate nickel or nickel alloy layer, thereby forming a portion of the surface. The particulate nickel or nickel alloy layer is typically prepared as the final layer (i.e., the outermost layer) on the substrate.

[0061] This method can be performed using all common nickel or nickel alloy electrodeposition equipment, such as by rack plating or barrel plating. Typically, the electrolyte is thoroughly mixed during deposition, for example by stirring or circulating the device. Stirring is preferred, for example, at a speed of 100 to 700 revolutions per minute (rpm).

[0062] In this method, a metal or metallized substrate serves as the cathode connection. For example, it can be a metal element, such as an electronic component, like a contact, switch part, or electrode. The metal or metallized substrate can be composed wholly or partially of one or more metals. Examples of metals include aluminum, silver, copper, nickel, noble metals such as palladium or platinum, steel, stainless steel, brass, and / or bronze. Metal layers suitable for electrophoretic coating, i.e., metallized plastics, particularly metallized plastics having layers of copper, nickel, silver, and / or noble metals such as palladium or platinum, can also be used as the substrate. For example, the production of metallized plastics is described in DE 21 26 781 C1 or WO 2020 / 225052A1. Here, the process can be performed similarly to the chemical deposition process of particulate nickel or nickel alloy layers described below.

[0063] The surface to be coated can be cleaned beforehand using conventional methods, such as degreasing. One or more layers, such as a layer composed of copper, nickel and / or silver, can also be coated on the substrate before depositing the particulate nickel or nickel alloy layer, which can improve the adhesion of the particulate nickel or nickel alloy layer to the substrate.

[0064] For example, a nickel anode can be used as the anode. This allows for simple control of the nickel ion content in the electrolyte. Multiple anodes can also be used.

[0065] Furthermore, this method offers great flexibility in its implementation. Specifically, deposition can be performed over a wide range of current densities, for example, from 0.1 to 10 A / dm³. 2 Preferably 0.5 to 5 A / dm 2 Even better, 1 to 4 A / dm 2 .

[0066] In this method, the nickel or nickel alloy layer containing particles can be deposited substantially uniformly, i.e., with a fairly uniform particle distribution. According to another embodiment, electrodeposition can be performed such that the particles (and / or other particles, if present) have a gradient. For example, the particle concentration on the inner side of the nickel or nickel alloy layer can be higher than the particle concentration on the outer side. Preferably, the particle concentration on the outer side of the nickel or nickel alloy layer is higher than the particle concentration on the inner side.

[0067] For example, gradients can be achieved by altering the mixing method, changing the current density, or varying the particle concentration during the deposition process. More thorough mixing typically results in the incorporation of more particles. Higher current densities generally lead to an increase in the amount of nickel or nickel alloy deposited. Furthermore, multiple electrolytes can be used, such as electrolytes with varying particle concentrations, nickel ion concentrations, and / or concentrations of other metal or non-metal compounds, to enable multi-step electrophoretic coating of the substrate.

[0068] In principle, this method can be used to prepare particulate nickel or nickel alloy layers of any desired thickness. For example, particulate nickel or nickel alloy layers can be formed with a layer thickness of up to 200 µm or up to 100 µm. Typically, the deposition thickness of the particulate nickel or nickel alloy layer is 4 to 50 µm, preferably 5 to 30 µm, and more preferably 5 to 20 µm. The layer thickness is measured using X-ray fluorescence spectroscopy according to DIN EN ISO 3497 (2001-12), for example, using a Fischerscope XDAL X-ray fluorescence spectrometer, with a maximum layer thickness of 20 µm. For layers thicker than 20 µm, the layer thickness is determined by microscopy on a cross-section of the layer. The deposition process typically results in a nickel or nickel alloy thickness greater than the particle thickness.

[0069] Another aspect of the present invention provides a plating solution for electrodepositing particulate nickel or nickel alloy layers. The plating solution comprises: - Nickel ions at concentrations of 2 to 200 g / L; - The particles are selected from at least one of the following: inorganic piezoelectric particles, conductive ceramic particles and combinations thereof, wherein the total concentration of the particles is 1 to 200 g / L; - At least one dispersant selected from the following: anionic dispersants, nonionic dispersants, and combinations thereof; - Optionally, ions selected from other metals: transition metals, noble metals and combinations thereof, wherein the total concentration of the ions of said other metals is at most 50 g / L; - At least one reducing agent, said reducing agent being capable of reducing nickel ions to nickel, and being capable of reducing other metal ions to other metals if other metal ions are present; - water.

[0070] The pH of the plating solution is from 3.0 to 12.0. Preferably, the pH is from 5.0 to 9.0. The plating solution used for electrodeposition is also referred to as "plating solution" below. This plating solution represents a composition in which a particulate nickel layer or a particulate nickel alloy layer can be electrodeposited without charge through one or more chemical reactions. This other metal is different from nickel.

[0071] Surprisingly, research has found that the plating solution according to the invention can also electrolessly deposit a particulate nickel or nickel alloy layer on a substrate. As mentioned above, the substrate can be a metallic substrate or a metallized substrate. Furthermore, as described below, optional seeded plastic substrates can also be coated. Advantageously, a layer with good adhesion and density, i.e., a layer with no or almost no pores, can be deposited.

[0072] The advantages described can be similarly obtained when combining electrodeposited nickel or nickel alloy layers with a dispersed electrolyte or electrodeposited nickel or nickel alloy layers. Electrodeposited particulate nickel or nickel alloy layers comprise particles at least partially arranged on the surface, along with nickel or nickel alloy. Nickel and nickel alloys may contain unavoidable impurities.

[0073] The nickel content of nickel alloys is typically 70 wt% or higher, preferably 85 wt% or higher, and more preferably 90 wt% or higher. Electrodeposited nickel alloys may contain other metals, sulfur, and / or phosphorus as additional components.

[0074] The concentration of nickel ions in the plating solution is 2 to 200 g / L. Specifically, the concentration of nickel ions present in the plating solution is 5 to 180 g / L, preferably 10 to 160 g / L, more preferably 20 to 150 g / L, and even more preferably 40 to 140 g / L.

[0075] The concentration of ions of optional other metals selected from transition metals, noble metals, and combinations thereof in the plating bath may be up to 50 g / L, preferably up to 30 g / L, and more preferably up to 10 g / L. These other metals are preferably selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au, and combinations thereof. Particularly preferably, one or more of the metals are selected from Fe, Co, Sn, and Bi. Other metals may be electroless deposited together with nickel.

[0076] Preferably, the plating solution is used for electrodepositing nickel layers and nickel alloys containing P and / or S, and contains no other metal ions except for unavoidable impurities.

[0077] In addition, the plating solution contains at least one reducing agent capable of reducing nickel ions to nickel, and, if present, reducing ions of other metals to other metals. Sufficient amounts of the reducing agent are used to reduce nickel and optionally other metals. Specifically, the concentration used is 1 to 100 g / L, preferably 5 to 50 g / L.

[0078] In this case, there are no particular limitations on the reducing agent; all reducing agents known to those skilled in the art for use in nickel chemical deposition can be used. The reducing agent preferably includes at least one of the following: hypophosphite, dimethylaminoborane, NaBH4, thiourea, thiocyanate, and combinations thereof. It is preferably composed of one or more of these reducing agents. The reducing agent can lead to the incorporation of non-metallic atoms during the electrodeposition process. For example, the exemplary reducing agents described above can lead to the incorporation of P atoms, S atoms, and / or B atoms, thereby obtaining a nickel alloy. Therefore, nickel alloys can also be prepared by electrodeposition without the use of other metal ions.

[0079] For preferred and alternative implementation schemes of the plating solution, please refer to the above-mentioned configurations regarding particles, their concentrations, alternative particles, dispersants, and the formation of dispersing electrolytes.

[0080] The preparation method of the plating solution is similar to that of a dispersed electrolyte, particularly by mixing the components and optionally heating to improve solubility. If necessary, the pH value can be adjusted as described above. As mentioned above, a complexing agent may also be optionally used.

[0081] Another aspect of the invention provides a method for electroless coating of a particulate nickel or nickel alloy layer onto a substrate. The method includes electroless deposition of a particulate nickel layer or a particulate nickel alloy layer onto the substrate using a plating solution for electroless deposition of a particulate nickel layer according to at least one of the embodiments described herein. The electroless deposition temperature is 15 to 95°C, preferably 50 to 95°C, more preferably 70 to 90°C.

[0082] The method for electrodepositing a particulate nickel or nickel alloy layer can obtain a coated substrate having a particulate nickel layer or a particulate nickel alloy layer, which achieves the aforementioned advantages. It can be a coated substrate as described in more detail below. In particular, the particulate nickel or nickel alloy layer is formed as the outermost layer. These particles are at least partially located at the surface of the particulate layer, thus forming part of the surface.

[0083] This method can be performed using all common apparatuses for electroless deposition of nickel or nickel alloy layers. Typically, the plating bath is mixed during deposition, for example, by stirring or circulating the apparatus. Stirring is preferred, for example, at a speed of 100 to 700 revolutions per minute.

[0084] According to a preferred embodiment, the substrate is arranged with the surface to be coated facing upwards, which facilitates the incorporation of particles into the nickel or nickel alloy layer. Mixing can control the particle deposition rate.

[0085] No voltage is applied during the electrodeposition process; the nickel or nickel alloy layer is deposited through a chemical reaction. The aforementioned metal or metallized substrates can be used. Alternatively, plastic substrates with polar surfaces, such as ABS or sulfonated or oxidized functionalized plastics, particularly sulfonated functionalized plastics, can be used directly. For example, the plastic can be functionalized as described in DE 21 26781 C1 or WO 2020 / 225052 A1, particularly as illustrated in the examples in these publications. Preferably, the polar or functionalized plastic is seeded before electrodeposition of the nickel or nickel alloy layer, as described, for example, in DE 21 26 781 C1 or WO 2020 / 225052 A1. During the seeding process, a metal seed (i.e., a seed composed of metal) is formed on the surface of the plastic, particularly the sulfonated plastic surface. The metal is preferably selected from the group consisting of: Pd, Ag, Au, Pt, Cu, Co, Ni, and Pd / Sn.

[0086] Typically, seeding is performed using a metal colloidal solution, or by first treating the plastic surface, particularly sulfonated plastic surfaces, with a noble metal ion solution, and then using a reducing agent to reduce the adsorbed noble metal ions into metal seeds. The use of such metal colloids is described, for example, in DE 196 11 137 and US 4,520,046.

[0087] The plastics are preferably selected from the group consisting of: polyacrylate-styrene-acrylonitrile, polyacrylonitrile-butadiene-styrene, polyamide, polyaramid, polyphthalamide, polyimide, polyetherimide, polyetheretherketone, polysulfone, polyethersulfone, polyphenylene sulfide, polyphenylene ether, polyvinyl chloride, polyethylene, polypropylene, polystyrene, syndiotactic polystyrene, polyester, polyurethane, epoxy resin and epoxy coating.

[0088] If necessary, the surface to be coated can be cleaned beforehand using conventional methods, such as degreasing. The substrate may be coated with one or more layers of copper, nickel, and / or silver before depositing the particulate nickel or nickel alloy layer.

[0089] In methods for electroless deposition of particulate nickel or nickel alloy layers, a gradient can be formed. For example, the gradient can be set by changing the particle concentration during the deposition process. Preferably, the gradient is set by using multiple plating solutions with different nickel ion concentrations and / or different particle concentrations, and these plating solutions are used to coat the substrate sequentially.

[0090] Furthermore, a granular nickel or nickel alloy layer of any desired thickness can be formed, particularly according to the embodiments described above for electrodeposition. Therefore, the above configurations and embodiments are also applicable to the method described above.

[0091] Another aspect of the invention describes a coated substrate having a particulate nickel layer or a particulate nickel alloy layer. The particulate nickel or nickel alloy layer comprises: - 100 parts by weight of nickel or nickel alloy, and - 0.5 to 250 parts by weight of at least one type of particles selected from the following: inorganic piezoelectric particles, conductive ceramic particles, and combinations thereof.

[0092] According to the preferred embodiment, the particulate nickel layer consists of nickel, particles, and any unavoidable impurities.

[0093] Nickel alloys typically consist of 65 wt%, preferably 75 wt% or more, more preferably 85 wt% or more, and even more preferably 90 wt% or more of nickel.

[0094] Nickel alloys specifically contain: - 0 wt% or more and 20 wt% or less of other metals, said other metals being selected from transition metals, noble metals and combinations thereof, and - 0 wt% or more and 15 wt% or less of elements selected from B, P, S, Se, Te, C and combinations thereof, And the remainder, consisting of nickel and any unavoidable impurities. In this case, the nickel alloy contains one of other metals and / or elements that are different from nickel.

[0095] For example, the decomposition of electrolyte components may produce unavoidable impurities, such as the incorporation of carbon, oxygen, nitrogen and / or boron.

[0096] According to a preferred embodiment, the nickel alloy containing the particulate nickel alloy layer comprises: - 0 wt% or more and 15 wt% or less, preferably 0 wt% or more and 10 wt% or less, more preferably 0 wt% or more and 5 wt% or less of other metals, said other metals being selected from transition metals, noble metals, and combinations thereof; and - 0 wt% or more and 10 wt% or less, preferably 0 wt% or more and 5 wt% or less, elements selected from B, P, S, Se, Te, C and combinations thereof, especially P, Se and / or S. And the remainder, consisting of nickel and any unavoidable impurities. In this case, the nickel alloy contains one of other metals and / or elements.

[0097] A particulate nickel or nickel alloy layer is typically formed on the outermost layer of a coated substrate. These particles are at least partially arranged on the surface of the particulate nickel or nickel alloy layer, thus forming part of the surface of the particulate nickel or nickel alloy layer or part of the outermost layer of the coated substrate.

[0098] The nickel or nickel alloy layer containing particles, in the case of 100 parts by weight of nickel in the nickel layer containing particles or in the case of 100 parts by weight of nickel alloy in the nickel alloy layer containing particles, particularly contains 1 to 200 parts by weight of particles, preferably 5 to 150 parts by weight of particles, more preferably 10 to 100 parts by weight of particles.

[0099] A coated substrate having a particulate nickel or nickel alloy layer can be obtained by methods for electrocoating a particulate nickel or nickel alloy layer onto a substrate, using a dispersing electrolyte according to at least one of the embodiments described herein, or by methods for electroless coating a particulate nickel or nickel alloy layer onto a substrate, using a plating solution according to at least one of the embodiments described herein. The aforementioned advantages are thus achieved.

[0100] According to the embodiment, the coated substrate is obtained by a method for electrodepositing a particulate nickel or nickel alloy layer. This particulate nickel alloy particularly comprises: - 0 wt% or more and 20 wt% or less, preferably 0 wt% or more and 15 wt% or less, more preferably 0 wt% or more and 10 wt% or less, even more preferably 0 wt% or more and 5 wt% or less of other metals, said other metals being selected from transition metals, noble metals, and combinations thereof, and - 0 wt% or more and 15 wt% or less, preferably 0 wt% or more and 10 wt% or less, more preferably 0 wt% or more and 5 wt% or less, elements selected from P, S, Se, Te, C and combinations thereof, especially P, Se and / or S. And the remainder, consisting of nickel and any unavoidable impurities. In this case, the nickel alloy contains one of other metals and / or elements. Other metals preferably include Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb, and combinations thereof, or are composed of the metals described above. Particularly preferably, the other metals comprise one or more metals selected from Fe, Co, Mo, and Cu, or are composed of the metals described above. The substrate is a metal or metallized substrate, as described herein.

[0101] Nickel alloys obtained by electrodeposition are preferably alloys of Ni and Fe, Ni and Co, Ni and Mo, Ni and Cr, Ni and Cu, Ni and P, Ni and S, Ni and Se, Ni and Fe and P, Se and / or S, Ni and Co and P, Se and / or S, Ni and Mo and P, Se and / or S, Ni and Cr and P, Se and / or S, or Ni and Cu and P, Se and / or S, in each case of which the alloy contains unavoidable impurities.

[0102] According to the embodiment, the coated substrate is obtained by a method for electroless deposition of a particulate nickel or nickel alloy layer. This particulate nickel alloy particularly comprises: - 0 wt% or more and 20 wt% or less, preferably 0 wt% or more and 15 wt% or less, more preferably 0 wt% or more and 10 wt% or less, and even more preferably 0 wt% or more and 5 wt% or less of other metals selected from transition metals, precious metals, and combinations thereof. - 0 wt% or more and 15 wt% or less, preferably 0 wt% or more and 10 wt% or less, elements selected from B, P, S and combinations thereof, especially P and / or S. And the remainder consisting of nickel and any unavoidable impurities. In this case, the nickel alloy contains one of other metals and / or elements. The other metals are preferably selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au, and combinations thereof. The other metals are particularly preferably selected from Fe, Co, Sn, Bi, and combinations thereof. The substrate is one of the substrates described in conjunction with the methods described above.

[0103] Furthermore, the aforementioned optional and preferred embodiments are similarly applicable to coated substrates. This is particularly applicable to substrates coated with a layer of nickel or nickel alloy containing particles, including layer thickness, particle size, optional other particles, and optional particle gradient.

[0104] If present, the other particles of the conductive carbon material exist in the particulate layer in an amount of 1 to 100 parts by weight, preferably 2 to 50 parts by weight, and more preferably 3 to 30 parts by weight, relative to 100 parts by weight of nickel in the particulate nickel layer or relative to 100 parts by weight of nickel alloy in the particulate nickel alloy layer. Therefore, the total amount of particles generally does not exceed 250 parts by weight, preferably 200 parts by weight, and more preferably 150 parts by weight, relative to 100 parts by weight of nickel in the particulate nickel layer or relative to 100 parts by weight of nickel alloy in the particulate nickel alloy layer.

[0105] Particulate nickel or nickel alloy layers exhibit good mechanical stability and corrosion resistance in weakly acidic, neutral and alkaline ranges (i.e., pH values ​​of 4 or more, especially 6 or more).

[0106] According to another embodiment, the hardness of the particulate nickel or nickel alloy layer is at least HV 200 (Vickers hardness), preferably at least HV 300, and more preferably at least HV 400. Measurements are taken at the surface in accordance with DIN EN ISO 14577-1 (2015-11). The hardness can be adjusted by the particulate content and (if present) the content of other particles.

[0107] The coated substrate exhibits corrosion resistance in weakly acidic ranges, and especially in alkaline ranges; it also exhibits lower overvoltage in aqueous alkaline media compared to substrates coated with a corresponding nickel or nickel alloy layer but without particles. Therefore, the coated substrate can be used as electronic components, particularly as switches, contacts, electrodes, or other components of electrochemical cells. It is preferably used as an electrode in electrochemical cells, for example, for chlor-alkali electrolysis or for electrolysis in water or aqueous alkaline media, for example, to generate oxygen and hydrogen. In each case, it can be used independently as an anode, cathode, or simultaneously as both.

[0108] Therefore, the dispersed electrolyte according to the invention and the plating solution according to the invention can be used to manufacture electronic components, particularly components for manufacturing switches, contacts, electrodes and electrochemical cells, preferably electrodes.

[0109] Another aspect of the invention provides an electrochemical battery comprising a coated substrate according to at least one embodiment. In this case, the coated substrate is preferably used as an electrode. It can be used independently as an anode and a cathode, and preferably as both simultaneously. Examples of electrochemical batteries include redox flow batteries, fuel cells, and electrolyzers.

[0110] According to the embodiment, the coated substrate is used as the cathode of the electrolytic cell. According to the invention, the anode may also be a coated substrate or other electrode, such as an electrode made of nickel or a nickel alloy, or an electrode coated with nickel or a nickel alloy.

[0111] Example The present invention will be described below through examples. However, it is not limited to these examples.

[0112] Measurement methods Use the following measurement methods.

[0113] 1) Layer thickness Layer thickness was measured using a Fischerscope XDAL X-ray fluorescence spectrometer according to DIN EN ISO 3497 (2001-12). The values ​​listed are average measurements.

[0114] 2) Composition According to DIN EN ISO 3497 (2001-12) standard, the composition of the particulate nickel or nickel alloy layer on the coated substrate surface was analyzed by X-ray fluorescence spectrometry using the above-mentioned equipment. The measured surface area was approximately 200 x 150 µm. The accuracy of the measurements was ±2 wt% or better.

[0115] 3) Vickers hardness According to DIN EN ISO 14577-1 (2015-11) standard, the surface hardness of the corresponding deposited layer is tested, which can be performed after surface polishing (i.e., treatment). Vickers hardness is represented by the symbol "HV". A 200 g weight is used for the test. The test time is 10 s. Vickers hardness is dimensionless.

[0116] Preparation of metal substrates The experiment used a stainless steel plate (1.4404) with dimensions of 50 x 120 x 0.4 mm. The paper was pretreated as follows:

[0117] RT = room temperature reagents Except for other reagents The following reagents were also used in the experiment.

[0118] Slotoclean AK 160 (containing NaOH and sodium metasilicate), SLOTOCLEAN EL DCG (containing NaOH, sodium metasilicate, and sodium carbonate), and SLOTOCLEAN BEF 30 (containing but-2-yn-1,4-diol and ethoxylated isothietrol) are products from Dr.-Ing. Max Schlötter.

[0119] Impact Nickel: Nickel electrolyte from Dr.-Ing. Max Schlötter for intermediate layer electrodeposition, containing 180 g / L NiCl2 according to DIN 50970 standard. 6H2O, 8 g / L HCl (concentrated), and water.

[0120] Nickel sulfamate plating solution MS: An aqueous solution of nickel sulfamate from Dr.-Ing. Max Schlötter, containing 160 g / L nickel ions, pH 4.0.

[0121] SLOTONIK M: A plating solution additive from Dr.-Ing. Max Schlötter containing 3 to 5 wt% alkyl ether sulfate (sodium salt form), with alkyl groups of C12-14 and an average of 2 ethylene oxide units in polyethylene glycol ether.

[0122] Barium titanate (BaTiO3, perovskite structure): particle size 0.8 µm (aspect ratio <3.0), purchased from Sigma-Aldrich, CAS No.: 12047-27-7.

[0123] Boron nitride (BN, hexagonal): approximately 1 µm in size, in plate form (aspect ratio > 3.0), purchased from Sigma-Aldrich, CAS No. 10043-11-5.

[0124] Titanium nitride (TiN): Particle size <3 µm (aspect ratio <3.0), purchased from Sigma-Aldrich, CAS No.: 25583-20-4.

[0125] Tamol ® Naphthalenesulfonic acid-formaldehyde condensate (sodium salt), purchased from BASF SE.

[0126] Examples 1 to 9 and Comparative Example 1 Electrolyte production For Examples 1 to 9 and Comparative Example 1 (CE1), electrolytes having the following components were prepared in a glass beaker (2 L).

[0127] - 375 mL / L nickel sulfamate plating solution MS (equivalent to 60 g / L nickel) - 34 g / L NiCl2 6H2O (equivalent to 8.4 g / L nickel) - 45 g / L boric acid - 8 mL / L SLOTONIK M (a plating solution additive containing dispersant) - 0.9 g / L of Tamol ® (Dispersant) - Distilled water - According to Table 1, it can be barium titanate (BaTiO3), boron nitride (BN), or titanium nitride (TiN).

[0128] To this end, NiCl2·6H2O, a dispersant, and boric acid were first added to a mixture of distilled water, nickel sulfamate solution, and plating solution additives, and the mixture was stirred at 60°C (500 rpm). To dissolve, the pH was adjusted to 4.1 by adding KOH. Then, for Examples 1 to 3, powdered barium titanate (BaTiO3) was slowly added; for Examples 4 to 6, powdered boron nitride (BN) was slowly added; and for Examples 7 to 9, powdered titanium nitride (TiN) was slowly added, and the mixture was dispersed by stirring (500 rpm). No particles were added in Comparative Example 1. The pH was adjusted to 4.0 by adding sulfamate. The amount of electrolyte used in each experiment was 2 L.

[0129] Table 1

[0130] Electrophoretic coating As described above, the stainless steel sheet is pretreated and pre-coated with a nickel layer. Each of the resulting metal substrates is then electrophoretically coated according to the following method.

[0131] In a 2L glass beaker, the electrolyte was mixed at 500 rpm using a 40 mm stir bar. Each of the stainless steel plates was connected to form a cathode and immersed in the electrolyte to a depth of 10 cm. Two nickel electrodes (25 x 120 x 5 mm) were arranged parallel to each other on either side of the cathode, spaced 4 cm apart, serving as anodes. The anodes were also immersed to a depth of 10 cm. The two parallel anodes were connected in series with the electrolyte, cathode, and DC power supply. Deposition was carried out at 60°C for 20 minutes at a current density of 2.5 A / dm³. 2 .

[0132] Assessment of sedimentary layers In each of Examples 1 to 9 and Comparative Example 1 (CE1), a dense, non-porous, and well-adhered nickel layer was deposited. The thickness of each layer was approximately 10 µm.

[0133] Figures 1 to 3 Scanning electron microscope images at 3000x magnification are shown for Examples 1 to 3. In Example 1, when the concentration in the dispersed electrolyte was 1 g / L, individual barium titanate particles were integrated into the nickel layer. Figure 2 and Figure 3 As shown, when the concentration of barium titanate in the dispersed electrolyte was 20 g / L and 40 g / L, respectively, more particles were incorporated into the layer in Examples 2 and 3. Particles at the nickel layer surface appeared as lighter-colored, clearly defined areas. Larger, rounder, and darker areas represented particles at lower positions coated with nickel. Figure 1 and Figure 3This indicates that barium titanate particles are incorporated into each nickel layer and are partially arranged on the surface of the nickel layers. In particular, in Examples 2 and 3, the incorporation is fairly uniform across the entire surface.

[0134] Figure 4 The image shown is from Comparative Example 1, where there are no particles in the nickel layer, at a magnification of 500x.

[0135] On the cross-section of the coated substrate, it was determined that barium titanate particles were also uniformly deposited within the particle-containing nickel layer of Examples 1 to 3. Figure 5A , 6A Figures 7 and 8 show optical micrographs of cross-sections of the coated substrates of Examples 2 and 3 and the coated substrate of Comparative Example 1. Figure 5A and 6A The particles in the coating can already be identified. Figure 5B and 6B Scanning electron microscope images of cross sections of Examples 2 and 3 are shown, at a magnification of 1500x.

[0136] Figures 8 to 10 Scanning electron microscope images of Examples 4, 5, and 6 are shown, with Example 4 showing a magnification of 5000x. Figure 8 The magnification of Examples 5 and 6 is 2000 times (respectively). Figure 9 and Figure 10 ). Figure 8 This shows that even at a concentration of 1 g / L in the dispersed electrolyte, boron nitride is incorporated into the nickel layer. For example... Figure 9 As shown, at a concentration of 10 g / L, more boron nitride particles are incorporated into the nickel layer. Figure 9 The lighter-colored areas reveal piezoelectric (i.e., non-conductive) boron nitride particles. Therefore, these boron nitride particles constitute part of the particle-containing nickel layer surface. Isolated aggregates of multiple particles were observed. Figure 10 As shown, when the concentration in the dispersed electrolyte is 20 g / L, more boron nitride particles are incorporated into the nickel layer. Particularly in Examples 5 and 6, the incorporation is quite uniform throughout the layer.

[0137] In the cross-sections of the coated substrates in Examples 4, 5, and 6, boron nitride particles were again found to be uniformly incorporated into the layer. Figure 11A and 12A Cross-sectional optical micrographs of Examples 5 and 6 are shown respectively. Figure 11B and 12B Scanning electron microscope images of them are shown.

[0138] Figures 13 to 15 Scanning electron microscope images of Examples 7, 8, and 9 at 500x magnification are shown. Figure 13This demonstrates the incorporation of titanium nitride particles into a nickel layer at a concentration of 1 g / L in a dispersed electrolyte. In Examples 8 and 9, at concentrations of 10 g / L and 20 g / L, respectively, more titanium nitride particles were deposited in the layer (see [references]). Figure 14 and Figure 15 ).

[0139] In the cross-sections of the coated substrates in Examples 7, 8, and 9, titanium nitride particles were again found to be uniformly incorporated into the layer. Figure 16A and 17A Cross-sectional optical micrographs of Examples 8 and 9 are shown respectively. Figure 16B and 17B Scanning electron microscope images of them are shown.

[0140] The compositions were determined for Examples 2, 3, 6, 8 and 9 and Comparative Example 1 (CE1) (see Table 2).

[0141] Table 2

[0142] It is assumed that the measured C and O contents can be attributed to natural impurities or electrolyte components. In Examples 2 and 3, some of the O content can be attributed to barium titanate particles. The doping of barium titanate, boron nitride, and titanium nitride can be confirmed by the measured composition.

[0143] In addition, Vickers hardness (HV) was measured. The results are summarized in Table 3.

[0144] Table 3

[0145] The incorporation of particles is associated with an increase in the Vickers hardness of the layer.

[0146] Overvoltage measurement The overvoltage was measured in a Gaskatel electrochemical cell (Flexcell PP) with a sample surface area of ​​3 cm². 2 The overvoltage of alkaline water electrolysis was measured in 30% aqueous KOH. The potential of the observed current was determined for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, a coated substrate was used as the electrode in the chamber and connected as either the cathode or anode, respectively. A standard hydrogen electrode (Gaskatel Hydroflex) was used as the reference electrode. The counter electrode used was made of wound Pt wire.

[0147] At 25°C, the current is -10 mA (-3.3 mA / cm). 2The potential measured at 0 V minus the theoretical potential of the hydrogen evolution reaction (HER), or at 25 °C with a current of 10 mA (3.3 mA / cm²), is taken as the potential measured at 0 V. 2 The potential measured at the time of oxygen evolution reaction (OER) minus the theoretical potential of OER plus 1.23 V is considered an overvoltage. The smaller the absolute value of the overvoltage, that is, the closer the measured value is to 0, the lower the overvoltage.

[0148] The results are summarized in Table 4.

[0149] Table 4

[0150] Compared to Comparative Example 1, the overall overvoltage was reduced by incorporating a small amount of piezoelectric barium titanate in Example 1 or a small amount of piezoelectric boron nitride in Example 4; specifically, it was reduced by approximately 0.2 V. The overvoltage for hydrogen generation was significantly reduced, while the overvoltage for oxygen generation was slightly increased.

[0151] In Examples 2 and 3, the effect was significantly enhanced by increasing the incorporation of barium titanate particles, and in Examples 5 and 6, the effect was significantly enhanced by increasing the incorporation of boron nitride particles. In Examples 3 and 6, the overvoltage was reduced by approximately 0.6 V overall. It was observed that the overvoltage for hydrogen formation could be significantly reduced. Compared to Comparative Example 1, the overvoltage for oxygen formation was slightly increased.

[0152] Therefore, it was confirmed that the incorporation of piezoelectric barium titanate particles or piezoelectric boron nitride particles can reduce overvoltage in aqueous alkaline media. A significant reduction in overvoltage was observed at higher particle concentrations.

[0153] Using titanium nitride (a conductive ceramic material), a significant overall reduction in overpotential was observed, approximately 0.4 V, even with a low particle content in the dispersed electrolyte of Example 7. Increasing the particle concentration in the nickel layer did not result in any observed reduction in overvoltage compared to the piezoelectric materials barium titanate and hexagonal boron nitride; instead, the overvoltage remained substantially constant. Conductive ceramic titanium nitride may reduce overvoltage through other mechanisms different from the piezoelectric particles in Examples 1 through 6.

[0154] As shown in Examples 1 to 9, the coated substrates in Examples 1 to 9 are suitable as anodes, and particularly suitable as cathodes for electrolysis in aqueous alkaline media. In particular, the overvoltage of the cathode reaction (i.e., hydrogen generation) is significantly reduced.

Claims

1. A dispersed electrolyte for electrodepositing a particulate nickel or particulate nickel alloy layer, said dispersed electrolyte comprising: - Nickel ions at concentrations of 2 to 200 g / L; - The particles are selected from at least one of the following: inorganic piezoelectric particles, conductive ceramic particles and combinations thereof, wherein the total concentration of the particles is 1 to 200 g / L; - At least one dispersant selected from the following: anionic dispersants, nonionic dispersants, and combinations thereof; - Optionally, ions selected from at least one of the following other metals: transition metals, noble metals and combinations thereof, wherein the total concentration of the ions of the other metals is at most 40 g / L; - Optionally, a nonmetallic compound, different from the dispersant and selected from at least one of the following: phosphorus compounds, sulfur compounds, selenium compounds, tellurium compounds, carbon compounds, and combinations thereof, wherein the total concentration of the nonmetallic compound is at most 50 g / L; and - water, in, The pH value of the dispersed electrolyte is 2.0 to 7.

0.

2. The dispersed electrolyte according to claim 1, wherein, The particles are selected from BN (hexagonal crystal system), AlN, ZnO, GaPO4, and M1. 2y MA 1-y [MB x Ti 1-x O3, M1 2y MA 1-y MC x Zr 1-x O3, M1 2y MA 1-y [MD x Mn 1-x O3, M1 2y MA 1-y [ME x Hf 1-x O3, M1[MF x Nb 1-x O3, M1[MG x V 1-x O3, M1[MH x Ta 1-x O3, TiN, TiC, TiB2, Ti2CN, B4C, WC and combinations thereof, wherein the following conditions apply in the general formula: M1 is independently selected from at least one element selected from Li, Na and K, preferably Li; MA is independently selected from at least one element selected from Ca, Sr, Ba, Pb and La; MB is selected from Zr, Hf, Mn, Mg 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 MC is selected from Hf, Mn, and Mg. 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 MD is selected from Hf and Mg 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ME is selected from Mg 1 / 3 Nb 2 / 3 Mg 1 / 3 V 2 / 3 Mg 1 / 3 Mn 2 / 3 and Mg 1 / 3 Ta 2 / 3 ; MF is selected from V, Ta and Mn; MG is selected from Ta and Mn; MH is Mn; x independently satisfies 0≤x≤1 in each case; and y independently satisfies 0≤y≤1 in each case.

3. The dispersed electrolyte according to claim 2, wherein, The particles are selected from BN (hexagonal crystal system), AlN, ZnO, GaPO4, and Li2[Zr]. x Ti 1-x O3, Li 2y MA 1-y [Zr x Ti 1-x O3、MA[Zr x Ti 1-x O3, Pb[Zr x Ti 1-x O3, LaMnO3, and LiNbO3 and combinations thereof, wherein MA is independently selected from at least one element in each case: Ca, Sr, and Ba; x independently satisfies 0 ≤ x ≤ 1 in each case; and y independently satisfies 0 ≤ x ≤ 1 in each case. <y<1。 4. The dispersible electrolyte according to any one of the preceding claims, wherein, The weight ratio of nickel ions to the other metal ions in the dispersed electrolyte is 80:20 or higher, preferably 85:15 or higher, more preferably 90:10 or higher, even more preferably 95:5 or higher, and / or The weight ratio of nickel ions to all phosphorus, sulfur, selenium, tellurium and carbon atoms in the at least one nonmetallic compound is 85:15 or higher, preferably 90:10 or higher, and more preferably 95:5 or higher.

5. The dispersible electrolyte according to any one of the preceding claims, wherein, The other metals include at least one element selected from the following: Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb, and combinations thereof, and / or The nonmetallic compound comprises at least one compound selected from the following: hypophosphite, urea, thiourea, thiocyanate, selenourea, lithium bis(trifluoromethanesulfonyl)imide, dimethyl telluride, xanthate, carbamate, ketone, aromatic aldehyde, sulfonated castor oil, and combinations thereof.

6. The dispersible electrolyte according to any one of the preceding claims, wherein, The dispersant comprises at least one anionic dispersant selected from: sulfate compounds having alkyl groups, aralkyl groups or aromatic groups, each of which has up to 30 carbon atoms; sulfonate compounds having alkyl groups, aralkyl groups or aromatic groups, each of which has up to 30 carbon atoms; and polymers containing carboxyl or carboxylate groups.

7. The dispersed electrolyte according to claim 6, wherein, The anionic dispersant comprises at least one first anionic dispersant and at least one second anionic dispersant, wherein the first anionic dispersant is selected from sulfate compounds having alkyl groups having 6 to 24 carbon atoms, sulfate compounds having aralkyl groups having 6 to 24 carbon atoms, and combinations thereof, and the second anionic dispersant is selected from sulfonate compounds having aromatic groups having 6 to 24 carbon atoms.

8. A plating solution for electrodepositing particulate nickel or nickel alloy layers, the plating solution comprising: - Nickel ions at concentrations of 2 to 200 g / L; - The particles are selected from at least one of the following: inorganic piezoelectric particles, conductive ceramic particles and combinations thereof, wherein the total concentration of the particles is 1 to 200 g / L; - At least one dispersant selected from the following: anionic dispersants, nonionic dispersants, and combinations thereof; - Optionally, ions selected from other metals: transition metals, noble metals and combinations thereof, wherein the total concentration of the ions of said other metals is at most 50 g / L; - At least one reducing agent capable of reducing nickel ions to nickel and, if present, reducing ions of the other metal to the other metal; and - water, in, The pH of the plating solution is between 3.0 and 12.

0.

9. The plating solution according to claim 8, wherein, The reducing agent comprises at least one reducing agent selected from the following: hypophosphite, dimethylaminoborane, NaBH4, thiourea, thiocyanate, and combinations thereof, and / or The other metals are selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au, and combinations thereof.

10. A method for electrophoretically coating a substrate with a particulate nickel or nickel alloy layer, the method comprising electrodepositing the particulate nickel or nickel alloy layer on a metal or metallized substrate at a temperature of 20 to 85°C using a dispersible electrolyte according to any one of claims 1 to 7.

11. A method for electroless coating a substrate with a particulate nickel or nickel alloy layer, the method comprising electrolessly depositing the particulate nickel or nickel alloy layer on the substrate using a plating solution according to claim 8 or 9 at a temperature of 15°C to 95°C.

12. A coated substrate having a particulate nickel or nickel alloy layer, wherein, The particulate nickel or nickel alloy layer comprises: - 100 parts by weight of nickel or nickel alloy, and - A total of 0.5 to 250 parts by weight of particles selected from at least one of the following: inorganic piezoelectric particles, conductive ceramic particles, and combinations thereof.

13. The coated substrate according to claim 12, wherein, The nickel alloy contains at least 65 wt% nickel.

14. The coated substrate according to claim 12, wherein, The nickel alloy comprises: - 0 wt% or more and 20 wt% or less of other metals selected from: transition metals, precious metals and combinations thereof; and - 0 wt% or more and 15 wt% or less of elements selected from the following: B, P, S, Se, Te, C and combinations thereof. And, the remainder consisting of nickel and any unavoidable impurities, and The nickel alloy contains other metals and / or one of the elements.

15. The coated substrate according to claim 14, wherein, The other metals are selected from Fe, Co, Mo, Cr, Cu, Zn, Sn, Bi, Sb and combinations thereof, and the element is selected from P, S, Se, Te, C and combinations thereof, or The other metals are selected from Fe, Pd, Re, Ru, Sn, Cu, Co, Bi, Au and combinations thereof, and the element is selected from B, P, S and combinations thereof.

16. An electrochemical cell comprising a coated substrate according to any one of claims 12 to 15.

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